India should not wage war on Pakistan because of the 2008 terrorist attacks for many reasons, but primarily because doing so is not an effective way to prevent terrorism in the future. War creates more hostility and promotes further acts of terrorism. The best way to reduce terrorism is to improve communication and intercultural understanding through conversation and negotiation. Violence begets violence, so war is never the answer.
The terrorism that occurred in India was not sponsored by the country of Pakistan. It was an independent action by those terrorist groups. Therefore India should instead seek out the terrorist groups that were responsible for the acts, instead of going after the country itself. Innocent lives will be saved and money will be saved in this way.